1. Field of the Invention
This invention relates to gas turbine engine exhaust nozzles and, more particularly, to seals for use between divergent flaps of axisymmetric vectorable exhaust nozzles.
2. Description of the Prior Art
Variable area axisymmetric nozzles are well known in the field and employed in such engines as the General Electric F110 engine. The exhaust nozzles of such engines use convergent divergent flaps and seals to aerodynamically control the exhaust flow to transform the pressure and thermal energy of the combustion discharge airflow into velocity and forward thrust for the engine. The manner and means to provide such nozzles are shown in many publications including U.S. Pat. Nos. 4,176,792, 4,245,787, and 4,128,208 entitled "Variable Area Exhaust Nozzle", Arthur McCardle, Jr., "Variable Area Nozzle System", Wilbert B. Freid, "Exhaust Nozzle Flap Seal Arrangement", Edward W. Ryan, et al, assigned to the same assignee and incorporated herein by reference. A new function, namely thrust vectoring, has been added to this type of nozzle as represented by an invention developed at the General Electric Company.
For an understanding of how the individual flaps and seals interrelate and operate to form the overall nozzle and thrust vectoring function, reference may be made to the patent application Ser. No. 336,369 entitled "Axisymmetric Vectoring Exhaust Nozzle", Thomas P. Hauer et al, filed with the present application and assigned to the same assignee. Interflap sealing for axisymmetric convergent divergent nozzles has always posed an interesting problem and challenge to gas turbine engine nozzle designers as evidenced by the many designs, arrangements and patents, some of which are cited herein.
Conventional nozzles including ones with variable throat and exit areas employ nozzle flaps and nozzle flap seals that pivot through the same angles or change their attitude with respect to an engine centerline generally simultaneously so there is no circumferential variation in their respective attitudes or pivot angle with respect to an engine or nozzle centerline. The axisymmetric vectoring nozzle adds a new dimension to an already difficult problem namely how to seal between two surfaces whose orientation or attitude is constantly changed. The present invention addresses the sealing problems of an interflap seal which provides sealing between two adjacent divergent flaps that are pivoted through different angles from one and other and with respect to an engine centerline. Each flap can be pivoted in a coning motion relative to the convergent flap or other other nozzle element to which it is attached. Another way of describing the problem is that there is a circumferential variation in nozzle flap attitudes with respect to an engine or nozzle centerline.
As with all nozzle and gas turbine engine system designs it is desirable that they be light weight, easy and relatively inexpensive to manufacture, maintain and repair and be highly durable in a high temperature and stress environment.
Accordingly, a primary object of the present invention is to provide sealing between nozzle flaps of a gas turbine engine axisymmetric vectoring exhaust nozzle.
Another object of the present invention is to provide sealing between the divergent flaps of a gas turbine engine axisymmetric vectoring variable exhaust nozzle.
Another object of this invention is to provide sealing between divergent flaps of a gas turbine engine axisymmetric vectoring variable exhaust nozzle wherein adjacent flaps are rotated through different angles or attitudes with respect to the nozzle centerline during vectoring operations.
Yet another object of this invention is to provide sealing between the divergent flaps which maintains axial and circumferential sealing integrity throughout the range of circumferential variation in nozzle flap attitudes with respect to the nozzle centerline.
A further object of the present invention is to provide sealing means between the divergent flaps of an axisymmetric vectoring variable exhaust nozzle which is light in weight and easy to manufacture and repair.
Yet another object of the present invention is to provide seal segments for an interflap seal for use in an axisymmetric vectoring variable exhaust nozzle that facilitate the repair and maintenance of the seal and nozzle.
These objects and other features and advantages become more readily apparent upon reference to the following description when taken in conjunction with the appended drawings.